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Commit d5f3da8d authored by Konstantin Vyshetsky's avatar Konstantin Vyshetsky
Browse files

fastbootd: use O_DIRECT for write partition 



Direct writes for partition flashing significantly increase performance.
Use O_DIRECT flag when opening partition for flashing. Additionally use
a 4096b aligned buffer which is required for O_DIRECT.
Switch from using 8MB write buffer to 1MB write buffer, as the extra
allocation has no performance impact.

Test: flash locally and reach home screen
Bug: 205151372
Signed-off-by: default avatarKonstantin Vyshetsky <vkon@google.com>
Change-Id: I060f438cf698d0fda1e59e35338bb5dc1cd05b51
parent 81cc119e

fastboot/device/flashing.cpp

+15 −3
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include "flashing.h"



#include <fcntl.h>

#include <string.h>

#include <sys/stat.h>

#include <unistd.h>
@@ -77,9 +78,20 @@ void WipeOverlayfsForPartition(FastbootDevice* device, const std::string& partit 


int FlashRawDataChunk(int fd, const char* data, size_t len) {

    size_t ret = 0;

    const size_t max_write_size = 1048576;

    void* aligned_buffer;



    if (posix_memalign(&aligned_buffer, 4096, max_write_size)) {

        PLOG(ERROR) << "Failed to allocate write buffer";

        return -ENOMEM;

    }



    auto aligned_buffer_unique_ptr = std::unique_ptr<void, decltype(&free)>{aligned_buffer, free};



    while (ret < len) {

        int this_len = std::min(static_cast<size_t>(1048576UL * 8), len - ret);

        int this_ret = write(fd, data, this_len);

        int this_len = std::min(max_write_size, len - ret);

        memcpy(aligned_buffer_unique_ptr.get(), data, this_len);

        int this_ret = write(fd, aligned_buffer_unique_ptr.get(), this_len);

        if (this_ret < 0) {

            PLOG(ERROR) << "Failed to flash data of len " << len;

            return -1;
@@ -147,7 +159,7 @@ static void CopyAVBFooter(std::vector<char>* data, const uint64_t block_device_s 


int Flash(FastbootDevice* device, const std::string& partition_name) {

    PartitionHandle handle;

    if (!OpenPartition(device, partition_name, &handle)) {

    if (!OpenPartition(device, partition_name, &handle, O_WRONLY | O_DIRECT)) {

        return -ENOENT;

    }